With rapid development of electronic science and technology and related research fields in recent years, square wave generators have been widely applied in fields of electronic science and technology, communications, physics, chemistry, biology, and even medical science. Square waves with high-speed and high-precision can be applied to situations such as ultrasonic, radar, medical imaging, communications, and laser control, and to frontier scientific research fields such as electron paramagnetic resonance, nuclear magnetic resonance, and mass spectrometry. With rapid development of modern science and technology and experimental methods, there are new requirements on square waves generating function with high-speed and high-precision.
In conventional technology, two common solutions are applied to generate the square waves with high-speed and high-precision. One solution is combining an FPGA and high-speed serialization technology, and a resolution of the square wave may be controlled to be 2 ns by using a high-speed clock. Generally, a (Double Date Rate) DDR is adopted to store waveform data, and communication with a master computer for transmitting a waveform parameter is achieved via an Ethernet or a PCI bus. The digital logics of the FPGA reads the waveform parameters from the DDR, and outputs a waveform by using the high-speed serialization technology after completing the waveform analysis. According to the above solution, square waves generating function with a high speed can be achieved, but the square wave only has a precision with an order of magnitude of nanosecond (ns), and thus failing to meet a requirement of high precision. Meanwhile, a minimum limit of a width of the square wave is 12 ns according to a waveform data storage framework based on DDR3. Another solution is using a DTC (Digital to Time Convert, digital-to-time converter) based on a vernier caliper method or a high-performance delay PLL (Phase Locked Loop), with which a time precision of picosecond or even sub-picosecond can be achieved. However, although square wave pulses with high precision can be outputted, there are some limitations for the high-precision DTC based on the vernier caliper method or based on the PLL. For example, a maximum width of an outputted pulse is limited, and a dead time of the output pulse is long, where the dead time can even reach microseconds.
Therefore, an issue for those skilled in the art to address is to provide a square wave generator which can continuously output the square wave with high precision, large dynamic range and low dead time and to provide a method for generating the square wave.